Multi-fuel oil furnace

ABSTRACT

A multi-fuel oil furnace system includes a burner that may use waste oil for fuel, and a heat exchanger for providing a warmed air output from the burning of the waste oil. The burner need not require a reservoir for continuously keeping the fuel hot as may be required by conventional systems. The burner may also include a user replaceable unit that may minimize down time of the burner for the user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional patent application No. 61/236,216, filed Aug. 24, 2009, and to U.S. Provisional patent application No. 61/238,435, filed Aug. 30, 2009, the disclosures of each being incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a multi-fuel furnace and, more particularly, to a burner and heat exchanger of an oil furnace that is capable of burning used motor oil, transmission oil, fuel oil, mineral oil, cooking oil, and the like.

Multi-oil furnaces are similar to standard oil burning furnaces, but have been adapted to handle oil products that have been previously used in a traditional lubricating operation, such as used crankcase oil, used transmission fluid, and even #2, #4 and #5 fuel oils. Such oil products can have significantly varying viscosities and significantly varying burning characteristics as well. Typically, used oil products are collected into a tank to be supplied to the furnace from a single source. As furnaces are normally operated when the ambient air temperatures are sufficiently cold to warrant the use of the furnace, the supply of used oil to the furnace is normally as cold as the ambient temperature, which requires a preheating of the used oil to more efficiently effect a burning of the used oil products.

The burner nozzle combines a flow of compressed air with the flow of preheated used oil to atomize the used oil and inject a stream of compressed air and atomized used oil droplets into the burner chamber of the multi-oil furnace where it is ignited to create a flame and provide a heat source. Known multi-oil furnace burner nozzles utilize an in-line burner nozzle configuration coupled directly to the front door of the multi-oil furnace.

Existing systems keep oil in a reservoir hot at all times for immediate firing. When there is no call for heat, on average about half the time, the electricity used for keeping the oil in the reservoir hot is wasted. The oil continually heated in the reservoir becomes carbonized and requires professional servicing.

Furthermore, multi-oil furnaces often require servicing more frequently than conventional fuel oil furnaces due to the fuel being burned. The required servicing can result in significant down time for the user.

As can be seen, there is a need for a multi-oil furnace that may be rapidly serviced by the user and may function without requiring a source of continually heated oil in a reservoir.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a multi-fuel burner comprises an air compressor disposed for delivering air to a nozzle; a fuel line disposed for delivering fuel to the nozzle; at least one heater adapted to warm the fuel; a controller adapted to control the air delivered from the air compressor, the delivery of fuel through the fuel line, and the warming of the fuel; and a replaceable unit comprising the heater, the nozzle, and an electrode, the replaceable unit being removably attached to the housing, wherein the replaceable unit is removable and replaceable by a user upon failure of one of the components of the replaceable unit.

In another aspect of the present invention, a heat exchanger comprises a main chamber disposed for receiving a flame and hot gases from a burner; a first set of heat fins surrounding an external circumference of the main chamber; a second chamber with a set of heat fins disposed inside of the second chamber; and a flame barrier disposed on the end of the second chamber.

In a further aspect of the present invention, a heating system comprises a multi-fuel burner comprising an air compressor disposed for delivering air to a nozzle; a fuel line disposed for delivering fuel to the nozzle; at least one heater adapted to warm the fuel; a controller adapted to control the air delivered from the air compressor, the delivery of fuel through the fuel line, and the warming of the fuel; and a replaceable unit comprising the heater, the nozzle, and an electrode, the replaceable unit being removably attached to the housing, wherein the replaceable unit is removable and replaceable by a user upon failure of one of the components of the replaceable unit; and a heat exchanger comprising a main chamber receiving a flame and hot gases from a burner; a first set of heat fins surrounding an external circumference of the main chamber; a second set of heat fins disposed inside of a second chamber; and a flame barrier disposed on the end of the second chamber.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a burner according to an embodiment of the present invention;

FIG. 2 is an exploded view of the burner of FIG. 1;

FIG. 3 is a front view of the burner of FIG. 1;

FIG. 4 is a perspective view of a user replaceable unit used in the burner of FIG. 1;

FIG. 5 is a perspective view of the burner of FIG. 1 with an igniter cover in an open position;

FIG. 6 is a perspective view of a heat exchanger, according to an embodiment of the present invention, adapted to be attached to the burner of FIG. 1;

FIG. 7 is an exploded view of the heat exchanger of FIG. 6;

FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 6; and

FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Various inventive features are described below that can each be used independently of one another or in combination with other features.

Broadly, an embodiment of the present invention provides a multi-fuel oil furnace system that includes a burner that may use waste oil for fuel, and a heat exchanger for providing a warmed air output from the burning of the waste oil. The burner need not require a reservoir for continuously keeping the fuel hot as may be required by conventional systems. The burner may also include a user replaceable unit that may minimize down time of the burner for the user.

Referring to FIGS. 1-5, a multi-fuel burner 10 may include an electrical box 12 for receiving power from a power supply. The face of the electrical box 12 may include one or more switches. For example, a fuel switch 14 may control the flow of fuel to the burner 10 and a run/prime switch 16 may prime the burner 10 with fuel. The electrical box 12 may also include one or more indicator lights, such as a heater light 23 for indicating that a fuel heater 20 is operational, a pump light 22 for indicating that a fuel pump (not shown) is operational, and a power light 24 for indicating power is being supplied to the electrical box 12.

The electrical box 12 may supply power to a burner motor 26. The burner motor 26 may turn a blower wheel 28. The blower wheel 28 may receive air through an adjustable shutter 77 (FIG. 2) and then through the air tube 52 to support combustion. An air gauge 50 may be visible from outside of the burner 10 and may indicate the air pressure being generated by the air compressor 32. Compressed air may be delivered, via the air line 36, into a replaceable unit 38, as shown in FIG. 5 and discussed in greater detail below. The replaceable unit 38 may mount onto a burner housing 40 and may be covered with a housing cover 42. The housing cover 42 may attach to the burner housing 40 via a hinge 70.

Fuel, such as used motor oil, transmission oil, fuel oil, mineral oil, cooking oil, and the like, may be delivered to the replaceable unit 38 through an oil inlet 44. An oil gauge 46 may be visible from outside of the burner 10 and may indicate the presence of oil pressure passing through the oil inlet 44.

A retention head 18 may be inserted onto the end of the burner tube 52 (see FIG. 1). An air tube and flange 52 may extend from the burner 10. The air tube 52 may deliver the flame from the burner 10 and hot exhaust air into the heat exchanger 80.

The electrical box 12 may supply power to a primary controller 54 which may control the flow of fuel and air to the burner. When a wall thermostat (not shown) calls for heat, the controller 54 may start the heaters 20, motor 26 and compressor 32 for a pre-purge. Typically, the pre-purge lasts for about 2 minutes, after which time the oil in the reservoir 62 is heated sufficiently to support combustion. After the pre-purge, the controller 54 may open a solenoid valve 72 and start an igniter 56, which may include an electrode 58 positioned at an outlet of a nozzle 60, and a fuel pump (not shown). The igniter 56 may be mounted on the cover 42. A thermostat 64 may be positioned at the nozzle block 62 for measuring the temperature of the heater block 62. Fuel may be delivered to the nozzle 60 via a fuel line 66. Air may be delivered to the nozzle 60 via an air line 68.

Once a flame is established by the burner 10, the flame may remain established until the wall thermostat is satisfied and breaks the circuit, which sends the controller 54 into a post-purge mode. In the post-purge mode, which may last about 2 minutes, the motor 26 may drive the blower 28 to clear the heat exchanger 80 of any remaining combustion properties and to clear the nozzle 60 of any latent oil. The heaters 20 may be energized during the entire time the controller 54 is active, including the pre-purge cycle, during flame production, and during the post-purge cycle. When the wall thermostat is not calling for heat, both of the heaters 20 may be dormant.

The replaceable unit 38 may contain the items most likely to cause a failure of the burner 10. For example, the replaceable unit 38 may include the nozzle 60, the electrode 58, the heaters 20 and the solenoid valve 72. The replaceable unit 38 may be removably attached to the housing 40. For example, studs 74 may extend from the housing. The studs 74 may fit into holes (not shown) in the face of the replaceable unit 38. Wing nuts 76 may be used to fix the replaceable unit 38 onto the housing 40. The housing cover 42 may be moved out of the way when installing and/or removing the replaceable unit 38 by pivoting the housing cover 42 about its hinge 70. Should a problem occur in one or more of the components of the replaceable unit 38, a user may simply remove the wing nuts 76 and slide the entire replaceable unit 38 out of the burner 10. The user would typically have a new replaceable unit 38 on hand to install in the burner while the damaged one is repaired or replaced. In this manner, a user may not be without heat for any extended period of time.

Referring now to FIGS. 6-9, the heat exchanger 80 may include an inlet 82 for insertion of the burner 10 (more specifically, for insertion of the retention head 18 and burner tube 52 of the burner 10) and a window 84 for viewing the flame generated by the burner. The flame of the burner 10 and hot gases may pass through the heat exchanger 80 and exit from an exhaust port 86.

A blower 90 may receive ambient air and pass that air through the heat exchanger 80. Trim rings 88 may be provided to help seal hot air from escaping the jacket. Warmed air may exit from an exhaust vent 92. While the heat exchanger 80 depicted in the Figures draws in ambient air and delivers warm air at the location of the furnace, additional duct work (not shown) and additional and/or separate blowers may be used to retrieve the ambient air from a remote location and to deliver the warmed air to a remote location.

Referring specifically to FIGS. 7-9, the heat exchanger 80 may be a “double pass” heat exchanger, wherein air flow may pass through two or more regions subject to heat from the burner 10. A main chamber 94 may attach to a door 96 of the heat exchanger 80. The main chamber 94 may receive the flame and heat from the burner 10. A plurality of external fins 98 may be disposed about an exterior circumference of the main chamber 94. Air may pass over the external fins 98 to be warmed by the flame and hot gases in the main chamber 94. The external fins 98 may be wrapped with a wrapping 100, for example a thin sheet of steel, to keep the air close to the main chamber 94. A secondary heat chamber 110 may include a secondary set of internal heat fins 102 may be disposed inside of the second chamber 110. An air deflector body 104, attached to an air deflector radius 106 may help control the flow of air through the internal heat fins 102. A flame barrier 108, typically made of stainless steel, may be attached to one end 114 (proximal to the flame of the burner 10) of the secondary heat chamber 110. A chamber ring 112 may be disposed at the other end 116 of the secondary heat chamber 110. The chamber ring 112 may be attached, such as by welding, onto the inside of the main chamber 94. Air baffles 118, disposed at each end of the steel wrapping 100, may permit air to flow from the external heat fins 98 through the exhaust vent 92.

The burner 10 described above may be used in conjunction with the heat exchanger 80. In an alternate embodiment of the present invention, the burner 10 may be used with different types of heat exchangers, for example, heat exchangers similar to those typically used in fuel oil burners. In another embodiment of the present invention, the heat exchanger 80 may be used with a different type of burner, for example, a conventional fuel oil burner.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A multi-fuel burner comprising: an air compressor disposed for delivering air to a nozzle; a fuel line disposed for delivering fuel to the nozzle; at least one heater adapted to warm the fuel; a controller adapted to control the air delivered from the air compressor, the delivery of fuel through the fuel line, and the warming of the fuel; and a replaceable unit comprising the heater, the nozzle, and an electrode, the replaceable unit being removably attached to the housing, wherein the replaceable unit is removable and replaceable by a user upon failure of one of the components of the replaceable unit.
 2. The multi-fuel burner of claim 1, further comprising a blower, controlled by the controller, for delivering combustion air to a heat exchanger.
 3. The multi-fuel burner of claim 1, further comprising a housing cover hingedly attached to the housing, the housing covering a hole in the housing, the hole permitting visual inspection of the replaceable unit when the housing cover is open.
 4. The multi-fuel burner of claim 1, further comprising a solenoid valve mounted on the replaceable unit, the solenoid valve controlling the flow of fuel to the nozzle.
 5. The multi-fuel burner of claim 1, further comprising studs protruding from the housing, the studs adapted to align with holes in a face plate of the replaceable unit.
 6. The multi-fuel burner of claim 5, further comprising removable nuts for securing the replaceable unit onto the studs.
 7. The multi-fuel burner of claim 1, including means for turning off the heater when the burner is not activated.
 8. The multi-fuel burner of claim 1, wherein the controller includes programming for running a pre-purge cycle prior to igniting the fuel, the pre-purge cycle permitting the fuel to be warmed by the heater.
 9. The multi-fuel burner of claim 1, wherein the controller includes programming for running a post-purge cycle after the ignition of the fuel is discontinued.
 10. The multi-fuel burner of claim 1, wherein the fuel is selected from the group consisting of motor oil, transmission fluid, mineral oil, fuel oil, cooking oil, and combinations thereof.
 11. A heat exchanger comprising: a main chamber disposed for receiving a flame and hot gases from a burner; a first set of heat fins surrounding an external circumference of the main chamber; a second set of heat fins disposed inside of a second chamber; and a flame barrier disposed on the end of the second chamber.
 12. The heat exchanger of claim 11, further comprising an air deflector disposed for directing an air flow over both the first set of heat fins and the second set of heat fins.
 13. The heat exchanger of claim 11, further comprising a blower disposed for pushing air through the heat exchanger.
 14. The heat exchanger of claim 11, further comprising an exhaust port disposed for expelling exhaust gases from the heat exchanger.
 15. The heat exchanger of claim 11, further comprising a steel wrapping wrapped around the first set of heat fins.
 16. The heat exchanger of claim 11, further comprising baffles disposed for directing a warmed air flow out through an exhaust vent of the heat exchanger.
 17. A heating system comprising: a multi-fuel burner comprising: an air compressor disposed for delivering air to a nozzle; an igniter for igniting the fuel through an electrode; a fuel line disposed for delivering fuel to the nozzle; at least one heater adapted to warm the fuel; a controller adapted to control the air delivered from the air compressor, the delivery of fuel through the fuel line, and the warming of the fuel; and a replaceable unit comprising the heater, a solenoid, a thermostat, the nozzle, and the electrode, the replaceable unit being removably attached to the housing, wherein the replaceable unit is removable and replaceable by a user upon failure of one of the components of the replaceable unit; and a heat exchanger comprising: a main chamber receiving a flame and hot gases from a burner; a first set of heat fins surrounding an external circumference of the main chamber; a second set of heat fins disposed inside of a second chamber; and a flame barrier disposed on the end of the second chamber.
 18. The heating system of claim 17, further comprising: a housing cover hingedly attached to the housing, the housing covering a hole in the housing, the hole permitting visual inspection of the nozzle when the housing cover is open; and a solenoid valve mounted on the replaceable unit, the solenoid valve disposed for controlling the flow of fuel to the nozzle.
 19. The heating system of claim 17, including means for turning off the heater when the burner is not activated.
 20. The heating system of claim 17, wherein the controller includes programming for running a pre-purge cycle prior to igniting the fuel, the pre-purge cycle permitting the fuel to be warmed by the heater. 